I have a 2001 extended cab longbed 4x4 with the 4R100. The truck has about 180,000 miles and the transmission groans just a bit in 1st when i pin it, which tells me it's pretty ragged out. The truck is the "fleet model" and it used to be a City of Boston work truck, which also tells me the trans has been run hard. I'm not that great at rebuilding transmissions, not exactly my cup of tea. But I'm always up for learning something new, so I went to the junkyard and got an old 4R100 from a junk truck. The transmission is burned out, I got it strictly to learn how to rebuild them. Once I can get to where I can rebuild all the parts, and assemble a working transmission, I plan on building it up to replace the one in my truck. I'm currently working with a K&N FIPK II intake, Diamond Eye 5" turbo back exhaust and a TS Performance 140+ 6 position chip. Other than that the engine is stock, but plan on gutting the EBPV from the pedestal, and have rebuilt the turbo already with a Garrett rebuild kit and dropped in an X-Wheel. (only because the old wheel had damage from rubbing the impeller housing.) My question is, when I rebuild this transmission, other than replacing the aluminum sun gear carrier with a steel one from an E4OD, and a Trans-Go Tugger valvebody kit, what considerations should I take as far as aftermarket parts or machining/replacement of current parts for longevity/ power handling capability? I plan on replacing the injectors with a stage 1 set and dropping in a Garrett PowerMax GTP-38 which will probably push me into the 450-500 hp area.